(1. 常州大學 材料科學與工程學院，常州 213164；
2. 常州大學 江蘇省材料表面科學與技術(shù)重點實驗室，常州 213164；
3. 中南大學 材料科學與工程學院，長沙 410083)
摘 要: 采用拉伸測試、金相顯微鏡、XRD及TEM等方法，研究時效處理對經(jīng)歷固溶+冷軋的7075鋁合金顯微組織和力學性能的影響規(guī)律。力學性能測試表明：80、100、120 ℃時效均能顯著提高合金強度并保持一定塑性。(475 ℃, 1 h固溶處理)+80%壓下量冷軋+(80 ℃, 48 h)時效合金的抗拉強度、屈服強度和伸長率分別為773 MPa、720 MPa和5%。顯微組織分析表明：相較于冷軋合金，時效合金強度的提高源于冷軋加工硬化(高的位錯密度、高的軋制織構(gòu)體積分數(shù)及細化的晶粒尺寸)和析出強化的共同作用；時效合金伸長率的改善與位錯回復程度和析出相特征同時相關(guān)。此外，根據(jù)時效析出和位錯回復特征，分析了時效過程中合金強度和伸長率的變化規(guī)律。
關(guān)鍵字: 7075鋁合金；形變熱處理；顯微組織；力學性能
（1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of ageing at 80, 100 and 120 ℃ on the mechanical properties and microstructures of 7075 Al alloy solution treated at 475 ℃ for 1 h and cold-rolled at room temperature by thickness reduction of 80% were studied by tensile test, optical microscopy, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Tensile test results show that the strength of the alloy is significantly improved by the thermomechanical treatment with acceptable ductility. Especially, after being aged at 80 ℃ for 48 h, the ultimate tensile strength, yield strength and elongation to failure of the alloy are 773 MPa, 720 MPa and 5%, respectively. Microstructural observations show that the strength of the alloy is attributed to the combination of cold-rolling work hardening (high dislocation density, increased rolling textures and refined grains) and precipitation strengthening. Meanwhile, the improved elongation of the alloy is mainly due to dislocation recovery and ageing precipitation. Furthermore, the change in strength and ductility of the alloy during ageing was analyzed further based on the dislocation density and precipitation characterization.
Key words: 7075 aluminum alloy; thermomechanical treatment; microstructure; mechanical property
